journal <str> backup (sequence <num>) already active

  Explanation:  An AIJ backup is already active for the  specified
  journal.   In  most cases, the previously active backup is being
  performed by the background AIJ  backup  server.   This  problem
  only  occurs when using the "by-sequence" AIJ backup option, and
  normally when specifying only a single AIJ sequence number value
  (i.e.  "/SEQUENCE=15").

  User Action:  Let the active backup finish before attempting  to
  start  another  AIJ backup operation, or specify both a starting
  and ending AIJ sequence number (i.e.  "/SEQUENCE=(15,15)").